Flash floods and landslides triggered by early monsoon rains have killed at least 560 people in northern India and left tens of thousands missing, officials said on Saturday, with the death toll expected to rise significantly.

Houses and small apartment blocks on the banks of the Ganges, India's longest river and sacred to Hindus, have toppled into the rushing, swollen waters and been swept away with cars and trucks.
 
Thousands of military servicemen are involved in rescue operations, with air force helicopters plucking survivors, many of them Hindu pilgrims and tourists, from the foothills of the Himalayas.

About 33,000 people had been rescued so far this week, according to the home ministry. Railways were running special trains from the devastated areas to take people home.

Media reports said authorities were struggling to rescue thousands of people stranded in flood-hit regions of northern India with little access to food or drinking water.

People remained stranded in some areas as flood waters and blocked roads made it difficult for rescue teams to reach them. Some survivors told NDTV news channel that they had no food for five days.

An Indo-Tibetan Border Police (ITBP) official told reporters on Friday most of the people stranded would be evacuated in a couple of days.

Internet search engine Google has launched a version of its Person Finder app to help people track missing relatives in the region.

Floods and landslides, caused by heavier-than-usual monsoon rains, left pilgrims and tourists trapped this week, mostly in Uttarakhand. Updated official numbers were not available but media reports estimated the number of dead to exceed 1,000.

"Whatever is humanly possible is being done," Manish Tewari, the minister of information and broadcasting, told reporters.

The rains had eased on Saturday but more rain is expected early next week.

Prime Minister Manmohan Singh has offered 200,000 rupees ($3,400) to each of the families of those who have lost their lives and 50,000 rupees ($840) to the injured from his national relief fund. He also pledged money to people who have lost their homes.

Singh promised 10 billion rupees ($167 million) to Uttarakhand, home to the gods in Hindu mythology and the hardest-hit state, for disaster relief.

So far, the rains have not hit the summer sowing season in northern India, as planting of rice, sugar, cotton and other agricultural produce is not yet in full swing.

Heavy rain early in the June-September season makes planting easier, but if flooding persists, stagnant water can delay sowing or damage early rice shoots.-Reuters